1. Field of the Invention
The present invention relates to a rotor type open-end spinning frame and a yarn ending or piecing method therefor.
2. Description of the Related Art
Of spinning frames, open-end spinning frames which require no roving by a roving frame, can improve the productivity and reduce the cost involving equipment investment, and are therefore widely used. Of the open-end spinning frames, a rotor type is the oldest and has proved as reliable over the years.
In this rotor type open-end spinning frame, a supply sliver is opened by a combing roller to separate impurities. Then, the opened fibers are transported into the rotor by an air stream produced in the fiber transport channel based on the negative pressure in the rotor that is spinning at a high speed, and are collected at the fiber collecting section at the largest inside-diameter portion of the rotor. A bundle of fibers collected at the fiber collecting section is drawn, while being twisted, from the yarn drawing passage, provided on the open side of the rotor coaxial to the rotor, by the action of the drawing roller, and is wound around a bobbin as a package. More specifically, the fiber bundle separated from the fiber collecting section is drawn along the wall of the yarn drawing passage, and at this time, the fiber bundle is drawn while rotating along the inner wall of the yarn drawing passage by the friction to that wall in accordance with the rotation of the rotor, so that the fiber bundle is temporarily twisted, helping the twist propagation of actual twisting.
The fiber bundle collected at the fiber collecting section sticks on the inner wall of the fiber collecting section only by the centrifugal force created by the rotation of the rotor. When the fiber bundle drawn along the yarn drawing passage is twisted, therefore, this twist is propagated to the fiber bundle sticking at the fiber collecting section, causing the fiber bundle in the fiber collecting section to rotate. Therefore, sufficient tension cannot be obtained at the time of twisting so that fibers are twisted while being insufficiently stretched. As a result, the fibers are not twisted straight, resulting in lower strength of yarn, disadvantageously.
As a solution to this problem, Japanese Unexamined Patent Publication No. 51-64034 discloses an apparatus as shown in FIGS. 46 and 47. In this apparatus, a disk-shaped draft rotor (inner rotor) 93 is provided inside an outer rotor 92 having a fiber collecting section 91. The draft rotor 93 makes differential rotation with respect to the outer rotor 92. Formed in the center of the draft rotor 93 is a hole in which a yarn introducing pipe (yarn drawing pipe) 94 is loosely fitted. This hole is perpendicular to a yarn drawing hole 95 for drawing a fiber bundle F collected at the fiber collecting section 91. The draft rotor 93 is provided with a small disk 96 (see FIG. 47) which revolves and rotates while being pressed against the fiber bundle F.
In this apparatus, the draft rotor 93 rotates faster than the outer rotor 92, with a predetermined rotational difference with respect to the outer rotor 92, to draw the fiber bundle F, collected at the fiber collecting section 91, out of the yarn drawing hole 95. Accordingly, this apparatus spins out the fiber bundle F while drafting it. Due to the action of the small disk 96, this apparatus spins out the fiber bundle F while drafting it, with suppressed floating of the fiber bundle F.
As the entrance of the yarn passage to guide the fiber bundle (fleece), separated from the fiber collecting section, is narrow in this conventional apparatus, the standard thread inserted into the yarn passage from the yarn drawing hole 95 reaches the fiber collecting section with difficulty at the time of yarn ending. This results in poor success in yarn ending.
As used throughout this specification it should be understood that "yarn ending" is intended to be synonymous with "yarn piecing".